Hi and welcome to Yorkietalk. According to this chart it says 3lbs 14oz but as everyone else has mentioned it is not always accurate as other things come into play as the size of the parents, genetics, etc.
Here is the link to the chart I used..
My Yorkshire Terrier puppy should grow to 3lb 14oz :: Find out how big your Yorkshire Terrier puppy will grow - Puppy Weight Estimates